1. Field of the Invention
The present invention relates to a signal detector and more particularly, to a signal detector, which alters its conditions of detection depending on the diversity of the environment.
2. Description of Related Art
In these days, various kinds of high technology products, such as cell phones, digital cameras, and pagers, have become essential in our daily lives. Following the advancement of technology, those high-tech products become smaller and more compact, but new problems have consequently developed.
For example, the cell phone nowadays can display both numerals and characters. With Internet service, a cell phone is able to have transnational and confidential communication, such as on-line chatting, which is hard to trace. If it is put to use in a crime, the investigation will encounter difficulties arising from the telecommunications aspects. Another example of the high-tech product is the pinhole camera, which is designed to be easily hidden and evil people take advantage of that feature. That is, many people's personal lives have been taped for sale or blackmail, which causes a sense of paranoia in the society. The foregoing high-tech products both have to rely on the transmission of signals to obtain information. Therefore, any illegal acts committed by using cell phones and pinhole cameras can be traced by detecting signals therefrom. However, prior art signal detectors are not able to automatically adapt to the environment and thus lack versatility.